Determinazione di 30 VOC’s in matrice acquosa mediante GC-MS in spazio di testa statico.

Il mercato dell’acquacoltura italiano ha presentato un forte incremento negli ultimi anni in risposta alla crescente domanda di prodotti ittici. I dati FAO sulla produzione mondiale da acquacoltura delineano, infatti, un mercato in rapida crescita con incremento del 5,9% dal 2000 al 2002 (1). In Europa la produzione è passata da una media di 1.448.000 tonnellate annue nel quinquennio 1990-1994 a 2.138.200 tonnellate nel periodo 2000-2004 (2). Più di mille i siti produttivi con una produzione di 71.900 tonnellate nel 2006

Supramolecular association in proton-transfer adducts containing benzamidinium cations. II. Concomitant polymorphs of the molecular salt of 2,6-dimethoxybenzoic acid with benzamidine

Two concomitant polymorphs of the molecular salt formed by 2,6-dimethoxybenzoic acid, C9H10O4 (Dmb), with benzamidine, C7H8N2 (benzenecarboximidamide, Benzam) from water solution have been identified. Benzamidinidium 2,6-dimethoxybenzoate, C7H9N2+center dot C9H9O4- (BenzamH(+)center dot Dmb(-)), was obtained through protonation at the imino N atom of Benzam as a result of proton transfer from the acidic hydroxy group of Dmb. In the monoclinic polymorph, (I) (space group P2(1)/n), the asymmetric unit consists of two Dmb(-) anions and two monoprotonated BenzamH(+) cations. In the orthorhombic polymorph, (II) (space group P2(1)2(1)2(1)), one Dmb(-) anion and one BenzamH(+) cation constitute the asymmetric unit. In both polymorphic salts, the amidinium fragments and carboxylate groups are completely delocalized. This delocalization favours the aggregation of the molecular components of these acid-base complexes into nonplanar dimers with an R-2(2)(8) graph-set motif via N+-H center dot center dot center dot O- charge-assisted hydrogen bonding. Both the monoclinic and orthorhombic forms exhibit one-dimensional isostructurality, as the crystal structures feature identical hydrogen-bonding motifs consisting of dimers and catemers

Heavy Metals Removal from Wastewater Using a Versatile Branched Polymer: Carboxylated Polyethy

The presence in the environment of large quantities of toxic heavy metals (i.e. cobalt, cromium, lead, cadmium, zinc, etc.), poses serious health risks to individuals, hence the development of novel methods to eliminate toxic contaminants from wastewaters in efficient and economically viable ways is highly desirable. In this work we assayed the ability of a polyamine polymer, polyethylenimine (PEI) and its carboxylated derivative PEI-COOH to complex a selection of twenty two heavy metals and remove them from a contaminated water by an ultra-filtration technique. We found that PEI is able to complex efficiently and reduce the concentration of eleven heavy metals (Ag, Al, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sn and Zn) to almost a third. In some cases, PEI is very efficient to remove also Cr and Sn to a concentration less than 0.1 ppm. Interestingly, PEI-COOH derivative is able to remove eight heavy metals (Ag, Al, Cd, Co, Cu, Ni, Pb, and Zn) to a concentration less than 0.4 ppm hence inc

Efficient Complexation-Ultrafiltration Process for Metal Ions Removal from Aqueous Solutions Using a Novel Carboxylated Polyethylenimine Derivative (PEI-COOH)

The presence of large quantities of toxic heavy metals (i.e. cobalt, chromium, lead, cadmium, zinc, etc.) in the environment may be a serious threat to humans. Hence, the development of novel methods able to eliminate these toxic contaminants from wastewater in efficient and economically viable ways is highly desirable. In this work we assayed the ability of two polymers, polyethylenimine (PEI) and its carboxylated derivative (PEI-COOH), to complex heavy metals and to remove them from contaminated water by polymer-assisted ultrafiltration. PEI is able to complex efficiently Ag, Al, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sn and Zn and reduce their concentration in permeate to values <4 ppm. Interestingly, PEI is very efficient to remove Cr and Sn down to a concentration less than 0.1 ppm. Moreover, PEI-COOH derivative is more efficient than PEI to remove Ag, Al, Cd, Co, Cu, Ni, Pb, and Zn to a concentration less than 0.4 ppm (ICP-OES analysis). Our preliminary results indicate that PEI-COOH is able to complex those metals that are not complexed by PEI, hypothesising that the combined use of these two polymers may be efficiently employed as a powerful strategy for the complete removal of heavy metals from wastewater